This invention relates to a closer mechanism, for urging a pivotally mounted wing member such as a door from an open position toward a closed position.
Compact size and simple form of a door closer is of advantage from the viewpoint of both the installation of the door closer and its outer appearance. In this respect an advantageous solution can be provided when a casing-like piston is utilized, to which force transmission occurs through a pinion arranged on a closer shaft located inside the piston. This kind of solution is disclosed for instance in the publication GB 2008666.
From the viewpoint of the operation of a door closer, for its part, it would be of advantage that the door could be opened by exerting a force of reasonable size and yet closing of the door could still be ensured. For this purpose different hydraulic arrangements and closer spring solutions may be utilized. In practice, however, these are rather complicated and often unsatisfactory as to their operation. In this respect utilization of an eccentric pinion provides a more simple solution, whereby the lever arm of the moment transmitted by the pinion changing during the opening movement of the door together with the changing force of the closer spring makes an advantageous operation of the door closer possible. Patent publication DE 821772 discloses one solution of this kind, which, however, is unsatisfactory especially from the viewpoint of utilization of space. Another solution is disclosed in patent publication EP 243786. In this case the drawbacks include manufacturing problems and costs caused by differently shaped teeth.